CN103645293B - Method for testing actuating pressure of explosion contact surface of explosive and test device - Google Patents

Abstract

The invention relates to a method for testing actuating pressure of an explosion contact surface of an explosive and a test device. According to the method, the purpose of test on the explosion pressure of the explosive under high temperature and high pressure (dozens of GPa) is achieved. The pressure on the explosion contact surface comprises change of pressure on the contact surface, which is caused by the pressure in an explosive detonation strengthening and attenuating process. Theoretical derivation for measuring the explosion pressure is realized by a higher mathematics calculus relation and value analysis method according to momentum conservation in order to realize measurement of the pressure on the explosion contact surface of the explosive. The test device is designed to comprise an explosion container, a throwing columnar rigid body, a high-speed camera, a data analysis system, a vacuum pump, a safety valve, a container for the throwing columnar rigid body, a detonation device and a scaleplate.

Description

A method for testing the action pressure of the explosive contact surface

technical field

The invention relates to a method for testing the action pressure of an explosive contact surface, especially for high-pressure testing in the current stage where direct testing at high temperature and high pressure is difficult.

Background technique

At present, although there are many methods to test the pressure, no one has proposed a direct test method for the pressure of the explosive explosion and the contact object. The explosive explosion process is high-speed, high-temperature and high-pressure. For example, the detonation pressure of PETN and RDX single-substance explosives can reach 30 according to the different explosive densities. ~50GPa, the explosion temperature can reach 4000K. The detonation pressure of commonly used industrial explosives is generally lower than that of the above simple explosives, but also reaches the order of tens of gigaPascals, while the detonation pressure of high-density and high-power military explosives is generally higher. Under such high temperature and high pressure conditions, there is currently no sensor that satisfies the conditions that can directly measure the detonation pressure. However, when explosives explode and come into contact with objects with a density greater than that of explosives, the acting pressure is greater than the detonation pressure. At present, researchers measure the shock wave pressure at different distances from the explosion of explosives, and then estimate the detonation pressure through the attenuation law of the shock wave in the air. The attenuation law of the shock wave, and the attenuation law of the shock wave in the air itself is not perfect, so there is a certain error in the method of estimating the detonation pressure, so further using the detonation pressure, the double law and the acoustic similarity to calculate the explosion pressure will also be There are certain errors. At present, researchers have proposed many methods for the detonation pressure test of explosives, including the free surface velocity method, the water tank method, the electromagnetic method and the manganin piezoresistive method in addition to the methods mentioned above, but none of them has given a method. A method of accurately measuring the pressure of an explosion.

201110116907.0 provides a method for testing the detonation performance of high-energy internal explosives. The method is to install a pressure sensor on the wall of a sealed explosion vessel, and the actual measured pressure is the pressure after the detonation product diffuses. This can be used as a basis for evaluating the performance of explosives, but the detonation pressure of explosives has not been measured.

201210400836.1 provides a high-temperature and high-pressure explosion limit tester, a method and application for determining the explosion limit. This invention is limited to the explosion test of the test gas with a maximum temperature of 400°C and a maximum pressure of 2.2MPa. Obviously, it cannot reach the explosion limit of the test explosive. condition.

201210369067.3 provides a multifunctional water mist suppression combustible gas explosion test system and test method, which also involves a pressure test, but the test conditions for explosive explosion cannot be realized.

Gu Pingan, Wei Haiying and Xiao Changyan from the Northwest Institute of Nuclear Technology researched on the FAE cloud detonation shock wave pressure test technology, and also proposed a method of using sensors to test the pressure of detonation shock waves at a certain distance, but it is also limited by sensors. performance, no method for directly testing the applied pressure on the detonation contact surface of the explosive is proposed.

Zhao Jibo, Tan Duowang, Li Jinhe and others from the Shock Wave Physics and Detonation Physics Laboratory of the Institute of Fluid Physics of the Chinese Academy of Engineering Physics have studied the near-field radial pressure of the explosion of cylindrical charges in water, and proposed to use a high-speed scanning camera to record the shock wave Velocity method and Rankine-Hugoniot relation are used to calculate near-field shock wave pressure, but this method is only a test of near-field shock wave.

Contents of the invention

In order to achieve the purpose of testing the explosive contact surface pressure, the invention provides a new testing method. The method can realize the purpose of testing high pressure (tens of gigapascals) at high temperature, and can also test the action pressure change of the contact surface in the whole process from unreacted to detonation of the explosive. The realization of this method provides a basis for studying the detonation mechanism of explosives and evaluating the performance of explosives. It can be used as an important index for evaluating the performance of explosives and provides an experimental basis for studying the performance of explosives.

The technical solution adopted by the present invention to solve the technical problem is: utilize the law of conservation of momentum to design a throwing cylindrical rigid body with an adjustable mass in contact with the explosive, use the data acquisition system to collect the motion of the throwing cylindrical body during the explosion of the explosive, and use the designed The data analysis system processes the data, and finally obtains the relationship between the pressure and time of the contact surface during the explosive explosion process, and the relationship between the pressure and time of the explosion contact surface.

Utilize the fundamentals of the momentum conservation test:

Ft＝mv＝I (1)

∫(P(t)S-mg)dt＝Δ(mv)＝mv (2)

In formula (2): P(t) is the pressure on the contact surface of the explosion at time t, S is the contact area between the experimental powder and the thrown cylindrical rigid body, mg is the gravity of the thrown cylindrical rigid body, and v is the velocity of the thrown cylindrical rigid body .

Transform (2) to get

_mv't +mg＝P(t)S (3)

In the formula: v' _t is acceleration, which can be obtained by data acquisition system and data analysis system.

The solution method of v' _t : use the high-speed camera to collect the data of the height H and time T of the throwing cylindrical rigid body designed below, and then use the data analysis system to fit the relationship between H and T. The relationship equation is as follows

H＝A ₁ +A ₂ T+A ₃ T ² +A ₄ T ³ +…+A _N+1 T ^N (4)

In the formula, A ₁ , A ₂ , A ₃ , A ₄ ... _AN+1 are undetermined coefficients, and v' _t can be obtained by deriving formula (4) twice.

According to formula (3), in the case of determining the acceleration at a certain moment, it is easy to calculate the corresponding pressure at this moment, so it can be calculated from the moment when the columnar rigid body starts to move until the explosion pressure reaches the detonation pressure, and then to the explosive detonation pressure Attenuation of the explosion contact surface pressure throughout the process. Therefore, using the above principles, the maximum explosion pressure and the explosion pressure during the growth and attenuation process of the detonation part can be determined.

In order to realize the above process, the present invention design includes the following parts: explosion container, throwing cylindrical rigid body, high-speed camera, vacuum pump, safety valve, throwing the container of cylindrical rigid body, detonator and steel ruler.

The explosion vessel is made of HT350 gray cast iron as the explosion vessel material. The tensile strength of HT350 gray cast iron is 350GPa, the elastic modulus is 130-160MPa, the compressive strength is 1100-1300MPa, and the shear strength is 350-500MPa. Based on the third strength theory of the strength condition (open cylinder) when the thick-walled cylinder is subjected to internal pressure and the pressure overpressure peak value of the explosive explosion acting on the vessel, the size of the designed explosion vessel can be calculated. The diameter of the explosive charge is 38mm, and the design outer diameter 350mm, 120mm internal diameter of the explosion vessel can meet the requirements of a primary charge of 0.10kgTNT equivalent, the diameter of the explosive charge is 38mm, and the pressure of the 0.10kgTNT equivalent explosive on the wall is 342.3MPa. The final size range of the explosion vessel is 350-450 mm in outer diameter, 120-150 mm in inner diameter, and 400 mm in height. A bracket is designed in the explosion vessel to install explosives.

The throwing cylindrical rigid body is made of gray cast iron with the grade of HT350, and the throwing cylindrical rigid body is a structure with adjustable quality. The structure mainly includes a base and a mass adjustment piece. The weight of the base is 50kg, and the weight of each adjusting piece is 20kg. The size of the throwing cylindrical rigid body is a cylindrical structure with a diameter of 500mm. According to the design in Fig. 4 and Fig. 5, the quality of the throwing cylindrical rigid body can be adjusted by increasing or decreasing the number of adjusting pieces. The mass range of the throwing cylindrical rigid body is 50-170kg.

For the selection of high-speed cameras, the positive pressure action time of the explosion shock wave is on the order of milliseconds, and the negative pressure and peak rise time are tens of microseconds. It is determined to choose a camera with a number of shots per second of 10 ⁶ or 10 ⁷ .

The data analysis system adopts a self-programmed software system. At present, there are many softwares used for experimental data analysis, and other software systems can also be used.

Vacuum pumps can choose general industrial vacuum pumps.

Safety valves serve two main purposes. 1. Ensure that the vacuum pump is not damaged by the blast wave. 2. When the vacuum pump stops working, it isolates the connection between the air and the internal vacuum of the throwing cylindrical rigid container.

The container for throwing a cylindrical rigid body is designed as a rectangular container, one side of which is the observation surface, the observation surface is made of high-strength transparent plastic steel, and the other surfaces are made of cast iron. The built-in buffer material of the flight container is a safety baffle. The container of the rigid body communicates with the air and the shock wave in the vertical direction is mainly introduced into the container, and the explosion of the explosive will not produce too much pressure on the container of the thrown cylindrical rigid body. The cast iron surface of the throwing cylindrical rigid body container is made of HT150 cast iron with a thickness of 10mm, and the high-strength transparent plastic steel is made of plastic steel with a thickness of 20mm. The height of the container is 2m, and the bottom surface is a square with a length and width of 1m.

The detonating device adopts the 8# instant detonator and MFB-200 detonator commonly used in the industry. The detonator is connected to the explosive and placed in the explosion container, and then connected to the detonator. The ruler adopts two steel rulers with a minimum scale of 0.5mm and a length of 1.5m. The two-day rulers are installed vertically on both sides of the high-strength transparent plastic-steel wall for reference to the height of the thrown cylindrical rigid body.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Figure 1 Front view of explosion vessel

Figure 2 Left view of the explosion vessel

Fig. 3 top view of the explosion vessel (the mark 1 in Fig. 3 is the explosion vessel, and the mark 2 is the bracket for placing explosives)

Figure 4 The front view and left view of the base of the throwing cylinder

Figure 5 Top view of the base of the throwing cylinder

Figure 6 The front view and left view of the throwing cylinder weight adjustment piece

Fig. 7 top view of throwing cylinder weight adjustment piece

The schematic diagram of the test system in Fig. 8 (the mark 1 in Fig. 8 is the explosion vessel, the mark 3 is the safety valve, the mark 4 is the safety baffle, which prevents the shock wave from producing excessive impact on the high-strength plastic steel surface, and the mark 5 is the throwing cylindrical rigid body container High-strength plastic-steel surface, on both sides of which are vertically placed altimeter scales, marking 6 is a throwing cylindrical rigid body, marking 7 is a high-speed camera, marking 8 is a vacuum pump, and marking 9 is a data analysis system)

Detailed ways

Establish the experimental test system as shown in Figure 8, at first the 100g explosive to be tested is connected with the detonator, and placed in the explosion container (mark 1 in Figure 8), so that the bottom diameter is 38mm and the throwing cylindrical rigid body (in Figure 8 Mark 6) close to each other, open the safety valve (mark 3 in Figure 8), start the vacuum pump (mark 8 in Figure 8), close the safety valve and then turn off the vacuum pump when the vacuum pump meter shows the vacuum state, turn on and debug the high-speed Video camera (mark 7 in Fig. 8), after the high-speed video camera works normally, start the video recording state, after getting ready, utilize detonator to detonate the detonator that is connected with the explosive to be tested, after the explosive is detonated, the throwing cylindrical rigid body will be thrown on the vertical Moving in the vertical direction, the ruler can display the motion height H of the throwing cylindrical rigid body, and use the high-speed camera to capture the moving image at the corresponding moment, that is, the size and height of the throwing cylindrical rigid body on the ruler at a certain moment, and use the self-programming to fit each moment The relationship between the time and height of the time and the height, and the equation (4) corresponds to each undetermined coefficient, and the equation (3) and (4) can be combined to obtain the pressure value of the explosion contact surface at each moment, including the maximum value of the explosion contact surface pressure of course .

Claims (1)

1. test a method for explosive charge interface pressure, the proving installation wherein designed comprises explosive container, throwing cylindricality rigid body, high-speed camera instrument, data analysis system, vacuum pump, safety valve, the container of throwing cylindricality rigid body, apparatus to cause bursting and scale; Wherein explosive container is characterized as: external diameter 350 ~ 450mm, internal diameter 120 ~ 150mm, and height is the cylindrical vessel of the HT350 casting pig casting of 400mm; Throwing Cylindrical Rigid body characteristics is: pedestal weight is 50kg, and each adjustment sheet weight is 20kg, and mass range is the right cylinder of the HT350 casting pig casting of 50 ~ 170kg; High-speed camera instrument is characterized as: shooting number per second is 10 ⁶or 10 ⁷video camera; Data analysis system is characterized as: self programming numerical fitting system; The container characteristics of throwing cylindricality rigid body is: vertically side is sightingpiston, and sightingpiston is the thick high-strength transparence plastic-steel of 20mm, and all the other each is cast iron face, cast iron face adopts thickness to be 10mmHT150 cast iron, container is rectangular parallelepiped, and container height is 2m, and bottom surface is the square that length and width are 1m; Apparatus to cause bursting is characterized as: industrial 8# instantaneous cap and MFB-200 blasting machine; Scale is characterized as: minimum scale is two steel rulers of 0.5mm, length 1.5m, and two scales are vertically arranged on the both sides of high-strength transparence plastic-steel wall respectively; The feature of its method of testing is for utilizing momentum conservation, and the method for higher mathematics calculous relation and numerical analysis realizes measuring explosive charge surface of contact high pressure, and the theory deduction process of method of testing is as follows,

Utilize the ultimate principle that momentum conservation is tested:

Ft＝mv＝I (1)

∫(P(t)S-mg)dt＝Δ(mv)＝mv (2)

In formula (2): P (t) is t blast surface of contact applied pressure, and S is the contact area of experiment powder column and throwing cylindricality rigid body, and mg is the gravity of throwing cylindricality rigid body, and v is the speed of throwing cylindricality rigid body; The conversion of (2) formula is drawn

mv′ _t+mg＝P(t)S (3)

In formula: v ' _tfor acceleration, data available acquisition system and data analysis system obtain;

V ' _tmethod for solving: utilize high-speed camera instrument to collect the height H of throwing cylindricality rigid body and the data of time T, recycle the relation that data analysis system simulates H and T, relation equation is as follows:

H＝A ₁+A ₂T+A ₃T ²+A ₄T ³+…+A _N+1T ^N(4)

A in formula ₁, A ₂, A ₃, A ₄a _n+1for undetermined coefficient, v ' can be drawn to the differentiate of (4) formula secondary _t;

According to (3) formula, when determining certain moment acceleration, calculating pressure corresponding to this moment, thus obtaining explosive charge surface of contact applied pressure process over time.